DEBT AND CREDIT FACILITIES - Schedule Of Long-Term Debt (Details) - USD ($) $ in Millions |
Sep. 30, 2021 |
Dec. 31, 2020 |
Apr. 24, 2020 |
Mar. 13, 2020 |
Debt Instrument [Line Items] |
Ìý
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Ìý
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Total Principal Amount |
$ 5,514
|
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Ìý
|
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Long-term Debt |
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|
$ 5,424
|
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|
Ìý
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Debt, Long-term and Short-term, Combined Amount |
5,376
|
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|
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|
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|
Long-term Debt, Current Maturities |
26
|
34
|
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|
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Total long-term debt |
5,350
|
$ 5,390
|
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ABL Facility |
Ìý
|
Ìý
|
Ìý
|
Ìý
|
Debt Instrument [Line Items] |
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|
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|
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|
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Long-term Line of Credit |
1,673
|
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|
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|
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Maximum borrowing capacity |
3,500
|
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|
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ÐÇ¿Õ´«Ã½ Inc. |
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|
Ìý
|
Ìý
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Ìý
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Debt Instrument [Line Items] |
Ìý
|
Ìý
|
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|
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|
Annual Effective Interest Rate |
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|
3.25%
|
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|
Ìý
|
ÐÇ¿Õ´«Ã½ Inc. | EDC Revolving Facilities - outstanding balance |
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Debt Instrument [Line Items] |
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Long-term Line of Credit |
55
|
$ 18
|
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|
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Maximum borrowing capacity |
80
|
$ 40
|
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|
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ÐÇ¿Õ´«Ã½ Inc. | ABL Facility |
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|
Ìý
|
Ìý
|
Ìý
|
Debt Instrument [Line Items] |
Ìý
|
Ìý
|
Ìý
|
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|
Annual Effective Interest Rate |
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|
2.15%
|
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|
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Maximum borrowing capacity |
$ 3,500
|
$ 3,500
|
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ÐÇ¿Õ´«Ã½ Inc. | 9.875% 2025 Senior Secured Notes |
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Debt Instrument [Line Items] |
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Stated interest rate |
9.875%
|
9.875%
|
9.875%
|
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Annual Effective Interest Rate |
10.57%
|
10.57%
|
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|
Ìý
|
Total Principal Amount |
$ 607
|
$ 955
|
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|
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|
Unamortized Debt Issuance Costs |
(4)
|
(8)
|
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|
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Unamortized (Discounts) |
(14)
|
(25)
|
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|
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Long-term Debt |
$ 589
|
$ 922
|
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ÐÇ¿Õ´«Ã½ Inc. | 6.750% 2026 Senior Secured Notes |
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Debt Instrument [Line Items] |
Ìý
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Stated interest rate |
6.75%
|
6.75%
|
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Annual Effective Interest Rate |
6.99%
|
6.99%
|
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|
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Total Principal Amount |
$ 845
|
$ 845
|
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|
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Unamortized Debt Issuance Costs |
(16)
|
(20)
|
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|
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Unamortized (Discounts) |
(8)
|
(9)
|
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|
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Long-term Debt |
$ 821
|
$ 816
|
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|
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ÐÇ¿Õ´«Ã½ Inc. | 1.500% 2025 Convertible Senior Notes |
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|
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|
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|
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Debt Instrument [Line Items] |
Ìý
|
Ìý
|
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|
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Stated interest rate |
1.50%
|
1.50%
|
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|
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|
Annual Effective Interest Rate |
6.26%
|
6.26%
|
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|
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Total Principal Amount |
$ 294
|
$ 296
|
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|
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Unamortized Debt Issuance Costs |
(3)
|
(4)
|
Ìý
|
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Unamortized (Discounts) |
(42)
|
(49)
|
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|
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Long-term Debt |
$ 249
|
$ 243
|
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|
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|
ÐÇ¿Õ´«Ã½ Inc. | 7.000% 2027 Senior Notes |
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Debt Instrument [Line Items] |
Ìý
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|
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|
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Stated interest rate |
7.00%
|
7.00%
|
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|
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Annual Effective Interest Rate |
9.24%
|
9.24%
|
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|
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|
Total Principal Amount |
$ 73
|
$ 73
|
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|
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|
Unamortized Debt Issuance Costs |
0
|
0
|
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|
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|
Unamortized (Discounts) |
(7)
|
(8)
|
Ìý
|
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Long-term Debt |
$ 66
|
$ 65
|
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|
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ÐÇ¿Õ´«Ã½ Inc. | 5.875% 2027 Senior Notes |
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|
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|
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|
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Debt Instrument [Line Items] |
Ìý
|
Ìý
|
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|
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Stated interest rate |
5.875%
|
5.875%
|
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|
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|
Annual Effective Interest Rate |
6.49%
|
6.49%
|
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|
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Total Principal Amount |
$ 556
|
$ 556
|
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|
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Unamortized Debt Issuance Costs |
(4)
|
(4)
|
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|
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Unamortized (Discounts) |
(16)
|
(18)
|
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|
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Long-term Debt |
$ 536
|
$ 534
|
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ÐÇ¿Õ´«Ã½ Inc. | 4.625% 2029 Senior Notes |
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Debt Instrument [Line Items] |
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Stated interest rate |
4.625%
|
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|
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Annual Effective Interest Rate |
4.63%
|
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|
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Total Principal Amount |
$ 500
|
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|
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Unamortized Debt Issuance Costs |
(8)
|
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|
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|
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Unamortized (Discounts) |
0
|
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|
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|
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Long-term Debt |
$ 492
|
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|
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|
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ÐÇ¿Õ´«Ã½ Inc. | 4.875% 2031 Senior Notes |
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Debt Instrument [Line Items] |
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Stated interest rate |
4.875%
|
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|
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|
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Annual Effective Interest Rate |
4.88%
|
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|
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|
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Total Principal Amount |
$ 500
|
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|
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|
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Unamortized Debt Issuance Costs |
(8)
|
Ìý
|
Ìý
|
Ìý
|
Unamortized (Discounts) |
0
|
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|
Ìý
|
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|
Long-term Debt |
$ 492
|
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|
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|
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ÐÇ¿Õ´«Ã½ Inc. | 6.250% 2040 Senior Notes |
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Debt Instrument [Line Items] |
Ìý
|
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|
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|
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Stated interest rate |
6.25%
|
6.25%
|
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|
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|
Annual Effective Interest Rate |
6.34%
|
6.34%
|
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|
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|
Total Principal Amount |
$ 263
|
$ 263
|
Ìý
|
Ìý
|
Unamortized Debt Issuance Costs |
(2)
|
(2)
|
Ìý
|
Ìý
|
Unamortized (Discounts) |
(3)
|
(3)
|
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|
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Long-term Debt |
$ 258
|
258
|
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|
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|
ÐÇ¿Õ´«Ã½ Inc. | ABL Facility |
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|
Ìý
|
Ìý
|
Ìý
|
Debt Instrument [Line Items] |
Ìý
|
Ìý
|
Ìý
|
Ìý
|
Annual Effective Interest Rate |
2.23%
|
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|
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|
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|
Long-term Line of Credit |
$ 1,673
|
$ 1,510
|
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|
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|
ÐÇ¿Õ´«Ã½ Inc. | 4.875% 2024 Senior Notes |
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|
Ìý
|
Ìý
|
Ìý
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Debt Instrument [Line Items] |
Ìý
|
Ìý
|
Ìý
|
Ìý
|
Stated interest rate |
Ìý
|
4.875%
|
Ìý
|
Ìý
|
Annual Effective Interest Rate |
Ìý
|
5.00%
|
Ìý
|
Ìý
|
Total Principal Amount |
Ìý
|
$ 395
|
Ìý
|
Ìý
|
Unamortized Debt Issuance Costs |
Ìý
|
(3)
|
Ìý
|
Ìý
|
Unamortized (Discounts) |
Ìý
|
(1)
|
Ìý
|
Ìý
|
Long-term Debt |
Ìý
|
$ 391
|
Ìý
|
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|
ÐÇ¿Õ´«Ã½ Inc. | 6.375% 2025 Senior Notes |
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|
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|
Ìý
|
Ìý
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Debt Instrument [Line Items] |
Ìý
|
Ìý
|
Ìý
|
Ìý
|
Stated interest rate |
Ìý
|
6.375%
|
Ìý
|
Ìý
|
Annual Effective Interest Rate |
Ìý
|
8.11%
|
Ìý
|
Ìý
|
Total Principal Amount |
Ìý
|
$ 64
|
Ìý
|
Ìý
|
Unamortized Debt Issuance Costs |
Ìý
|
0
|
Ìý
|
Ìý
|
Unamortized (Discounts) |
Ìý
|
(4)
|
Ìý
|
Ìý
|
Long-term Debt |
Ìý
|
$ 60
|
Ìý
|
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|
ÐÇ¿Õ´«Ã½ Inc. | 5.750% 2025 Senior Notes |
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|
Ìý
|
Ìý
|
Ìý
|
Debt Instrument [Line Items] |
Ìý
|
Ìý
|
Ìý
|
Ìý
|
Stated interest rate |
Ìý
|
5.75%
|
Ìý
|
Ìý
|
Annual Effective Interest Rate |
Ìý
|
6.01%
|
Ìý
|
Ìý
|
Total Principal Amount |
Ìý
|
$ 396
|
Ìý
|
Ìý
|
Unamortized Debt Issuance Costs |
Ìý
|
(3)
|
Ìý
|
Ìý
|
Unamortized (Discounts) |
Ìý
|
(4)
|
Ìý
|
Ìý
|
Long-term Debt |
Ìý
|
389
|
Ìý
|
Ìý
|
AK Steel | Industrial Revenue Bonds |
Ìý
|
Ìý
|
Ìý
|
Ìý
|
Debt Instrument [Line Items] |
Ìý
|
Ìý
|
Ìý
|
Ìý
|
Total Principal Amount |
Ìý
|
92
|
Ìý
|
Ìý
|
Unamortized Debt Issuance Costs |
Ìý
|
0
|
Ìý
|
Ìý
|
Unamortized Premiums |
Ìý
|
2
|
Ìý
|
Ìý
|
Long-term Debt |
Ìý
|
$ 94
|
Ìý
|
Ìý
|
AK Steel | Industrial Revenue Bonds due 2024 |
Ìý
|
Ìý
|
Ìý
|
Ìý
|
Debt Instrument [Line Items] |
Ìý
|
Ìý
|
Ìý
|
Ìý
|
Long-term Debt, Current Maturities |
$ 26
|
Ìý
|
Ìý
|
Ìý
|
AK Steel | 7.000% 2027 AK Senior Notes |
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|
Ìý
|
Ìý
|
Ìý
|
Debt Instrument [Line Items] |
Ìý
|
Ìý
|
Ìý
|
Ìý
|
Stated interest rate |
7.00%
|
7.00%
|
Ìý
|
Ìý
|
Annual Effective Interest Rate |
9.24%
|
9.24%
|
Ìý
|
Ìý
|
Total Principal Amount |
$ 56
|
$ 56
|
Ìý
|
Ìý
|
Unamortized Debt Issuance Costs |
0
|
0
|
Ìý
|
Ìý
|
Unamortized (Discounts) |
(5)
|
(6)
|
Ìý
|
Ìý
|
Long-term Debt |
51
|
$ 50
|
Ìý
|
Ìý
|
AK Steel | Industrial Revenue Bonds |
Ìý
|
Ìý
|
Ìý
|
Ìý
|
Debt Instrument [Line Items] |
Ìý
|
Ìý
|
Ìý
|
Ìý
|
Total Principal Amount |
92
|
Ìý
|
Ìý
|
Ìý
|
Unamortized Debt Issuance Costs |
0
|
Ìý
|
Ìý
|
Ìý
|
Unamortized Premiums |
2
|
Ìý
|
Ìý
|
Ìý
|
Long-term Debt |
$ 94
|
Ìý
|
Ìý
|
Ìý
|
AK Steel | 7.625% 2021 AK Senior Notes |
Ìý
|
Ìý
|
Ìý
|
Ìý
|
Debt Instrument [Line Items] |
Ìý
|
Ìý
|
Ìý
|
Ìý
|
Stated interest rate |
Ìý
|
Ìý
|
Ìý
|
7.625%
|
Annual Effective Interest Rate |
Ìý
|
7.33%
|
Ìý
|
Ìý
|
Total Principal Amount |
Ìý
|
$ 34
|
Ìý
|
Ìý
|
Unamortized Debt Issuance Costs |
Ìý
|
0
|
Ìý
|
Ìý
|
Unamortized (Discounts) |
Ìý
|
0
|
Ìý
|
Ìý
|
Long-term Debt |
Ìý
|
$ 34
|
Ìý
|
Ìý
|
AK Steel | 7.500% Senior Secured Notes due July 2023 |
Ìý
|
Ìý
|
Ìý
|
Ìý
|
Debt Instrument [Line Items] |
Ìý
|
Ìý
|
Ìý
|
Ìý
|
Stated interest rate |
Ìý
|
Ìý
|
Ìý
|
7.50%
|
Annual Effective Interest Rate |
Ìý
|
6.17%
|
Ìý
|
Ìý
|
Total Principal Amount |
Ìý
|
$ 13
|
Ìý
|
Ìý
|
Unamortized Debt Issuance Costs |
Ìý
|
0
|
Ìý
|
Ìý
|
Unamortized (Discounts) |
Ìý
|
0
|
Ìý
|
Ìý
|
Long-term Debt |
Ìý
|
$ 13
|
Ìý
|
Ìý
|
AK Steel | 6.375% 2025 AK Senior Notes |
Ìý
|
Ìý
|
Ìý
|
Ìý
|
Debt Instrument [Line Items] |
Ìý
|
Ìý
|
Ìý
|
Ìý
|
Stated interest rate |
Ìý
|
6.375%
|
Ìý
|
Ìý
|
Annual Effective Interest Rate |
Ìý
|
8.11%
|
Ìý
|
Ìý
|
Total Principal Amount |
Ìý
|
$ 29
|
Ìý
|
Ìý
|
Unamortized Debt Issuance Costs |
Ìý
|
0
|
Ìý
|
Ìý
|
Unamortized (Discounts) |
Ìý
|
(2)
|
Ìý
|
Ìý
|
Long-term Debt |
Ìý
|
$ 27
|
Ìý
|
Ìý
|